In an increasingly connected world, users try to find constant wireless network connectivity for their electronic devices. A user typically connects his device to a wireless network through wireless network access points. In order to maximize the utility of the wireless network, wireless network access points typically use omnidirectional antennas tuned to specific frequencies according to the IEEE 802.11 standards. More advanced wireless networks may include Multiple Input Multiple Output (MIMO) access points that include multiple sets of antennas. A MIMO access point imposes constraints on the size and materials of each individual antenna element.
A MIMO access point may include multiple antennas printed on a low permittivity substrate. Typically, the antennas in an access point are monopole antennas due to the size constraints of fitting multiple antennas under the radome of the access point. In order to accommodate dual-band standards, monopole antennas designs are typically designed with two additional monopole elements. In general, three monopoles sharing the same ground plane incur a relatively large amount of ripple and pattern irregularity, especially as the spacing between the elements decreases. These are challenges presented when the principal currents exist on the monopole and on the ground plane.